Adds support for vkBindIndexBuffer and vkDrawIndexed.
There is significant duplication currently between Draw::play and
DrawIndexed::play, but most of it is going to evaporate when we
solve the context stomping problems.

Bug: b/118619338
Change-Id: If8e9f7b1f11a3c763e73663733697fddd3e1fcac
Reviewed-on: https://swiftshader-review.googlesource.com/c/25508Reviewed-by: Ben Clayton <bclayton@google.com>
Reviewed-by: Alexis Hétu <sugoi@google.com>
Reviewed-by: Nicolas Capens <nicolascapens@google.com>
Tested-by: Chris Forbes <chrisforbes@google.com>
Kokoro-Presubmit: kokoro <noreply+kokoro@google.com>